Despite the large number of modifications proposed to the standard Cam-clay models over the last three decades, the critical state concept has been much less successful for modelling sand behaviour. This thesis is concerned with understanding the stress-strain and strength characteristics of Portaway sand, a quartz sand, and the validity of several recently developed critical state models formulated in terms of the state parameter concept. The laboratory investigation consisted of the evaluation and modification of two triaxial systems and 83 triaxial tests performed under monotonic and cyclic loading conditions. Emphasis has been placed on assessing the applicability of critical state theory and state parameter concept to sands. Portaway sand was chosen in this research work because it is a typical granular material for which the deformation behaviour can be obtained and used to verify the newly developed constitutive models. The critical state model concerned is known as CASM developed by Yu (1995, 1998). CASM is a relatively simple model because it only requires seven model constants, five of which are the same as those used in the modified Cam-clay model. Three extensions of CASM referred to as CASM-b, CASM-d and CASM-c were developed recently based on the combined hardening concept and the bounding surface plasticity theory. These enable the smooth transition of stiffness, phase transformation and cyclic behaviour to be simulated. For the first time, a simple procedure for determining all the model parameters from triaxial results has been established. The validities of the theoretical assumptions introduced in the new models are critically assessed in light of results obtained from both element testing and numerical modelling. In general, the overall stress-strain behaviour of Portaway sand observed in triaxial tests under various stress paths is well captured by the models.

The drilling industry, along with many others, is becoming increasingly competitive, demanding greater efforts to improve safety and reduce costs. For this reason, companies are progressively looking towards computerised automation to enhance performance. Unlike most industries however, the drilling industry has been slow to take advantage of the advances in computer and automation technology. Only recently have automatic operations such as tubular handling been placed under computer control. These activities relate to peripheral mechanical handling problems which are relatively easy to solve. The concept of an automatic intelligent drill, capable of making its own or assisted decisions about drilling parameters such as weight on bit or rotational speed, may seem remote and far into the future. Research in drilling automation, at the University of Nottingham, has the ultimate objective of achieving computerized drill control through the the application of an intelligent knowledge induction system. At the University, a laboratory rig has been developed with such a system installed. Decisions for optimal performance are based on either maximum penetration or minimum cost drilling. The system has a self-learning capability, allowing a progressive improvement in performance. The prototype system is currently undergoing trials, using real data collected while the laboratory rig is drilling and artificial data. The results are very encouraging and demonstrate the feasibility and advantages of optimised drill performance. This thesis describes the design and development of this drill optimisation scheme produced by the author. Both the theory behind the optimisation system, and the results of the initial phase of Laboratory testing are included.

This research describes an application of numerical methods for the prediction of strata methane flow into mine workings around a longwall coal face employing methane drainage. This method of methane prediction was developed by solving the time-dependent gas flow equation using the finite element analysis. Having obtained the gas pressure distribution throughout the finite element mesh, a mass flow equation was derived to calculate methane flow rate for a given mining boundary. A computer program for the prediction of methane flow was then developed by devising appropriate modifications and additions to a finite element package originally written for heat flow by PAFEC limited. Stress analysis was also carried out in order to provide an understanding of stress fields around a longwall face to evaluate the induced permeabilities under these stress fields. Three main routines of the original package required modifications to accommodate the solution of a different equation. These were element routines, solution routines and flux calculation routines. These routines, after modification, were used to simulate advance and retreat longwall mining, with and without drainage. Several different sensitivity tests were carried out by changing parameters such as borehole pressure, length, and spacing in order to aid the planning of methane drainage systems for longwall mining.

The minerals industry often requires people to work in hazardous environments, these environments are constantly increasing in size and complexity as organisations look for new more cost-effective ways of extracting resources. Not only does this size and complexity bring with it additional safety concerns, the introduction of new legislation has placed the responsibility of employee safety with the organisation. Safety has become an important consideration, where once it might have been viewed as costly and counterproductive, organisations are now seeking to gain competitive advantage in this area. Two key areas of a successful safety management programme are risk assessment and training. These are important in designing systems and environments that are as safe as possible and in educating and training personnel to operate safely within those environments. Virtual Reality (VR) technology is one tool that has been applied successfully to the training requirements across a wide range of industries. In the past two years there is evidence to show that VR technology is becoming more widely used, partly due to the reduced cost and a reduction in the perceived technological complexity. As the cost of computing falls and the fidelity of the virtual worlds increases, VR is considered a viable option for a number of applications. Two prototype VR systems were designed and built. The first, a risk visualisation system, enhances a virtual environment with a risk-based overlay. The relationships between dangerous areas and equipment can be visualised in 3D. It also provides a framework for evaluating the risk programmatically at an arbitrary location. The second is a surface mine simulator that uses a hazard identification system as a tool to aid the training of haul truck operators in surface mine. This system includes a world construction tool that allows users to import and prepare the terrain, construct the virtual world, and specify any hazards. The training system can evaluate the performance of a trainee in the virtual world using a simple scoring algorithm.

Nine types of Al-Ti, Al-Ti-C and Al-Ti-B master alloy rods have been investigated by metallography and also by LiMCA measurements after the dissolution of the alloys in an aluminium melt. The results show the presence of TiC and TiB2 particle clusters in the Al-Ti-C and Al Ti-B alloys, respectively. The size of the clusters as measured by LiMCA was in the range of 20-100µm. The percentage of the total TiB2 and TiC additions to the melt that was found in the clusters was up to 2.8%. EDX analysis of the TiC particle clusters showed the presence of oxygen, presumably in the form of aluminium oxide, and the TiB2 clusters also contained oxygen, fluorine and potassium. AI-5Ti-1B master alloys from different manufacturers contain different quantities of impurities containing oxide and fluoride salts. Furthermore, the distribution of phases varies, especially with respect to texturing of the TiB2 particles, and the impurities show a varying degree of association with the TiB2 texture lines. The Al-Ti-C master alloys also showed texturing but the main difference was observed in their oxide content. The quantity of clusters as determined by LiMCA can be related to the microstructure of the master alloys, further supporting the conclusion that oxide plays an important role in cluster formation in the Al-Ti-C rods and the impurities containing oxide and fluoride salts in the Al-Ti-B rods. The LiMCA tests also confirm that further agglomeration of the clusters and particles occurs in the aluminium melt both for Al-Ti-C and AI-Ti-B master alloys. The flow conditions and particle distribution in an aluminium melt in launders was modelled using CFD for two launder designs. In the first design the effect of vortex formation in the dead-zone at a corner of the launder was demonstrated. Particle dispersion from a point source simulating the dissolution of a master alloy rod was modelled for the second launder. An effective distribution was achieved within 1000 mm from the source of particle introduction, this distance being less than that required for the dissolution of the soluble TiAl3 particles from the master alloys. LiMCA measurements in the first launder and chemical analysis of samples taken from the flowing melt support the flow and particle distribution modelling.

Mine surveying is at present undergoing a revolution with the possibility of fully automating survey tasks. This has become possible because of the introduction of automated systems of data measurement, acquisition, processing and plotting. The field instrumentation required for automation is explained, together with an analysis of the results from numerous evaluation tests. A guide is given to the computer facilities necessary, both hardware and software, to achieve automation within the mine survey office. Emphasis is given to the experiences and results obtained from the field applications investigated, including underground surveys and surface volumetric surveys. The efforts to automate subsidence monitoring are also covered. The investigations have highlighted the overall increase in efficiency offered by such systems, and the possible future potential offered to the discipline is discussed.

Despite significant improvements in mine safety, underground mine fires and explosions are responsible for a significant number of deaths world-wide each year. The training of personnel in safety procedures has had a significant impact on reducing the frequency of injuries and fatalities. This thesis presents an innovative virtual reality simulation, 'Fire-VR', designed to enhance the visualisation of a mine ventilation system. Fire-VR incorporates existing ventilation network analysis procedures with a graphical front-end and offers considerable potential for user interactivity in training scenarios. The system, Fire-VR incorporates a suite of programs, created to model the mine infra-structure, ventilation system and environment of a typical mine. The key components include the ventilation modelling system (VentSim-VR) to simulate the flow of air through the mine network and an environment modelling system (EnvSim-VR) to simulate the effects of various external and internal influences on the quality of the ventilated air within the mine. The environmental system is able to model both pre-defined events (such as the liberation of firedamp from the strata) which can occur at certain times and also spontaneous events which occur when pre-determined criteria have been met. The system has been created with two main interfaces for the user to interact with. Firstly, the 2D interface shows a plan view of the mine network with the primary function of displaying environmental and ventilation information. Secondly, the 3D interface, used as the main virtual reality graphical front-end to the simulation provides the user with a rich semi-immersive virtual environment. It is suggested that Fire-VR can potentially be applied in the training of personnel at a significantly reduced cost and in a safe environment. To demonstrate this a number of possible training examples have been presented to showcase the potential of the Fire-VR software.

Borehole instabilities can be encountered at any stage in the life of a well and they are the main cause of drilling difficulties, resulting in substantial expenditures, expensive loss of time, sometimes even in the loss of part of or even whole boreholes. The main aim of this research is to use new method and theory in geomechanics to conduct the stability analysis of wellbore. The cavity contraction theory is used to get the new elastic-perfectly plastic solutions for vertical borehole with anisotropic stress field. The solutions for Mohr-Coulomb and Hoek-Brown criteria are derived in this paper. A new alternative criterion, which is to limit the radius of plastic zone around borehole, to predict the wellbore instability was also recommended. The finite element code ABAQUS is applied to analyse the mechanical behaviour of wells with different inclinations and different azimuths. A Generalized Plane Strain Model is used in the calculation. The failure wellbore pressure, borehole closure, plastic zone distribution of different direction wells are given in this paper. In order to accurately predict the wellbore behaviour in soft and porous rocks, a suitable and advanced constitutive model of rocks is the key issue of the borehole instability research. A new model, called CASM (Clay And Sand Model) which is based on critical state theory and formulated in terms of the state parameter concept is applied in this research. The non-coaxiality theory is incorporated into CASM to analyse the wellbore stability. Compared with coaxial model, non-coaxial model gives more pessimistic results. However, it was found that the influence of non-coaxiality on wellbore stability depended on initial conditions of wellbore.

Haulage Costs account for a considerable portion of a surface mine's operational budget. It is therefore vital that, for a particular pit configuration, the optimum utilisation of the available truck fleet is adopted during the mine's life. Also, if the optimisation methods are established beforehand, it is possible to determine exactly how many trucks will be required. Both decisions can be made at the planning stage by the application of linear programming and discrete simulation to computer models of the haulage network. The project presented herein investigates the practicality of developing a general-purpose mine transportation selection and scheduling system within the context of a Computer Aided Design (CAD) environment. Compatibility with a purpose-built, interactive graphics package is shown to enable rapid, semiautomatic generation of model networks and the planning engineer is assisted further by the robust and friendly user-interface which has also been developed. Unlike a number of existing packages, which either make use of commercially available software on a stand-alone basis or were specifically designed for the analysis of a particular operation, this system is completely integrated with a central database which makes it applicable to any mine. The enhanced ability to produce valid mathematical solutions and their associated network models using the above systems, allows a large number of configurations and dispatching policies to be compared in a relatively short space of time. However, attention is also paid to the degree of correspondence with what can be achieved in reality since this will also effect the selection decision. All the modules mentioned form part of a much larger planning system currently being developed at The University of Nottingham, Department of Mining Engineering, known as NUmine.

The work carried out in this thesis outlines some of the problems associated with abrasive wear in machines and other mechanical equipment used to excavate or process natural rock material. It has been stated that if the problems associated with abrasion are to be better understood, then a sound knowledge of the abrasive potential of rocks is essential. A number of common wear mechanisms are described together with existing hardness and abrasive tests. The author has investigated rock hardness and abrasiveness by the use of existing methods and subsequently, developed new correlated with the well tests which can be established methods of determining physical and mechanical properties of rock. A project on hard rock drilling has been conducted to determine the rate of wear on expensive diamond impregnated coring drill bits. A detailed investigation which involved the design and manufacture of special measuring equipment to accurately measure and record changes in the profile shape of the bit during its life span. This has permitted a study of the wear characteristics related to the various drilling parameters employed. A collaborative project was carried out with DeBeers, UK, to attempt to discover methods of predicting the rate of specific wear on diamond impregnated saw blades and the cutting forces required with the sawing of hard stone materials. This project has led to a new statistical approach to the analysis of the acquired test data for this purpose. A number of case histories have been discussed and recommendations made. As a result of these investigations together with the work covered in this thesis, the author has developed two new abrasive tests. These tests can be used to test materials such as unconsolidated rocks which otherwise, could not be satisfactorily tested by the established tests already in existence. The new tests have been tried and proved by correlating the test data by combining multiple regression analysis with the results obtained from physical and petrological rock property tests with actual rock cutting data. Conclusions have been drawn and recommendations for future work suggested.